graphql-engine/server/src-lib/Hasura/Backends/MSSQL/Instances/Execute.hs
Gil Mizrahi 59ab1bbe57 refactor Hasura.Backends.MSSQL.Instances.Execute
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/3265
GitOrigin-RevId: f7faa22be30ecc5a876dc40ad93cb8d2452de65e
2022-01-06 09:49:58 +00:00

412 lines
14 KiB
Haskell

{-# OPTIONS_GHC -fno-warn-orphans #-}
-- | Defines a 'BackendExecute' type class instance for MSSQL.
--
-- This module implements the needed functionality for implementing a 'BackendExecute'
-- instance for MSSQL, which defines an interface for translating a root field into an execution plan
-- and interacting with a database.
--
-- This module includes the MSSQL implementation of queries, mutations, and more.
module Hasura.Backends.MSSQL.Instances.Execute
( MultiplexedQuery' (..),
multiplexRootReselect,
)
where
import Control.Monad.Trans.Control (MonadBaseControl)
import Data.Aeson.Extended qualified as J
import Data.HashMap.Strict qualified as Map
import Data.HashMap.Strict.InsOrd qualified as OMap
import Data.HashSet qualified as Set
import Data.List.NonEmpty qualified as NE
import Data.Text.Extended qualified as T
import Database.ODBC.SQLServer qualified as ODBC
import Hasura.Backends.MSSQL.Connection
import Hasura.Backends.MSSQL.Execute.Delete
import Hasura.Backends.MSSQL.Execute.Insert
import Hasura.Backends.MSSQL.Execute.Update
import Hasura.Backends.MSSQL.FromIr as TSQL
import Hasura.Backends.MSSQL.Plan
import Hasura.Backends.MSSQL.SQL.Value (txtEncodedColVal)
import Hasura.Backends.MSSQL.ToQuery as TQ
import Hasura.Backends.MSSQL.Types.Internal as TSQL
import Hasura.Base.Error
import Hasura.EncJSON
import Hasura.GraphQL.Execute.Backend
import Hasura.GraphQL.Execute.LiveQuery.Plan
import Hasura.GraphQL.Namespace (RootFieldAlias (..), RootFieldMap)
import Hasura.GraphQL.Parser
import Hasura.Prelude
import Hasura.RQL.IR
import Hasura.RQL.Types
import Hasura.RQL.Types qualified as RQLTypes
import Hasura.RQL.Types.Column qualified as RQLColumn
import Hasura.SQL.AnyBackend qualified as AB
import Hasura.Session
import Language.GraphQL.Draft.Syntax qualified as G
instance BackendExecute 'MSSQL where
type PreparedQuery 'MSSQL = Text
type MultiplexedQuery 'MSSQL = MultiplexedQuery'
type ExecutionMonad 'MSSQL = ExceptT QErr IO
mkDBQueryPlan = msDBQueryPlan
mkDBMutationPlan = msDBMutationPlan
mkDBSubscriptionPlan = msDBSubscriptionPlan
mkDBQueryExplain = msDBQueryExplain
mkLiveQueryExplain = msDBLiveQueryExplain
-- NOTE: Currently unimplemented!.
--
-- This function is just a stub for future implementation; for now it just
-- throws a 500 error.
mkDBRemoteRelationshipPlan =
msDBRemoteRelationshipPlan
-- * Multiplexed query
newtype MultiplexedQuery' = MultiplexedQuery' Reselect
instance T.ToTxt MultiplexedQuery' where
toTxt (MultiplexedQuery' reselect) = T.toTxt $ toQueryPretty $ fromReselect reselect
-- * Query
msDBQueryPlan ::
forall m.
( MonadError QErr m
) =>
UserInfo ->
SourceName ->
SourceConfig 'MSSQL ->
QueryDB 'MSSQL Void (UnpreparedValue 'MSSQL) ->
m (DBStepInfo 'MSSQL)
msDBQueryPlan userInfo sourceName sourceConfig qrf = do
-- TODO (naveen): Append Query Tags to the query
let sessionVariables = _uiSession userInfo
statement <- planQuery sessionVariables qrf
let printer = fromSelect statement
queryString = ODBC.renderQuery $ toQueryPretty printer
odbcQuery = encJFromText <$> runJSONPathQuery (mssqlRunReadOnly $ _mscExecCtx sourceConfig) (toQueryFlat printer)
pure $ DBStepInfo @'MSSQL sourceName sourceConfig (Just queryString) odbcQuery
runShowplan ::
ODBC.Query -> ODBC.Connection -> IO [Text]
runShowplan query conn = do
ODBC.exec conn "SET SHOWPLAN_TEXT ON"
texts <- ODBC.query conn query
ODBC.exec conn "SET SHOWPLAN_TEXT OFF"
-- we don't need to use 'finally' here - if an exception occurs,
-- the connection is removed from the resource pool in 'withResource'.
pure texts
msDBQueryExplain ::
MonadError QErr m =>
RootFieldAlias ->
UserInfo ->
SourceName ->
SourceConfig 'MSSQL ->
QueryDB 'MSSQL Void (UnpreparedValue 'MSSQL) ->
m (AB.AnyBackend DBStepInfo)
msDBQueryExplain fieldName userInfo sourceName sourceConfig qrf = do
let sessionVariables = _uiSession userInfo
statement <- planQuery sessionVariables qrf
let query = toQueryPretty (fromSelect statement)
queryString = ODBC.renderQuery query
odbcQuery =
mssqlRunReadOnly
(_mscExecCtx sourceConfig)
( \conn -> liftIO do
showplan <- runShowplan query conn
pure
( encJFromJValue $
ExplainPlan
fieldName
(Just queryString)
(Just showplan)
)
)
pure $
AB.mkAnyBackend $
DBStepInfo @'MSSQL sourceName sourceConfig Nothing odbcQuery
msDBLiveQueryExplain ::
(MonadIO m, MonadBaseControl IO m, MonadError QErr m) =>
LiveQueryPlan 'MSSQL (MultiplexedQuery 'MSSQL) ->
m LiveQueryPlanExplanation
msDBLiveQueryExplain (LiveQueryPlan plan sourceConfig variables _) = do
let (MultiplexedQuery' reselect) = _plqpQuery plan
query = toQueryPretty $ fromSelect $ multiplexRootReselect [(dummyCohortId, variables)] reselect
mssqlExecCtx = (_mscExecCtx sourceConfig)
explainInfo <- (mssqlRunReadOnly mssqlExecCtx) (liftIO . runShowplan query)
pure $ LiveQueryPlanExplanation (T.toTxt query) explainInfo variables
--------------------------------------------------------------------------------
-- Producing the correct SQL-level list comprehension to multiplex a query
-- Problem description:
--
-- Generate a query that repeats the same query N times but with
-- certain slots replaced:
--
-- [ Select x y | (x,y) <- [..] ]
--
multiplexRootReselect ::
[(CohortId, CohortVariables)] ->
TSQL.Reselect ->
TSQL.Select
multiplexRootReselect variables rootReselect =
emptySelect
{ selectTop = NoTop,
selectProjections =
[ FieldNameProjection
Aliased
{ aliasedThing =
TSQL.FieldName
{ fieldNameEntity = rowAlias,
fieldName = resultIdAlias
},
aliasedAlias = resultIdAlias
},
ExpressionProjection
Aliased
{ aliasedThing =
ColumnExpression
( TSQL.FieldName
{ fieldNameEntity = resultAlias,
fieldName = TSQL.jsonFieldName
}
),
aliasedAlias = resultAlias
}
],
selectFrom =
Just $
FromOpenJson
Aliased
{ aliasedThing =
OpenJson
{ openJsonExpression =
ValueExpression (ODBC.TextValue $ lbsToTxt $ J.encode variables),
openJsonWith =
Just $
NE.fromList
[ UuidField resultIdAlias (Just $ IndexPath RootPath 0),
JsonField resultVarsAlias (Just $ IndexPath RootPath 1)
]
},
aliasedAlias = rowAlias
},
selectJoins =
[ Join
{ joinSource = JoinReselect rootReselect,
joinJoinAlias =
JoinAlias
{ joinAliasEntity = resultAlias,
joinAliasField = Just TSQL.jsonFieldName
}
}
],
selectWhere = Where mempty,
selectFor =
JsonFor ForJson {jsonCardinality = JsonArray, jsonRoot = NoRoot},
selectOrderBy = Nothing,
selectOffset = Nothing
}
-- * Mutation
msDBMutationPlan ::
forall m.
( MonadError QErr m
) =>
UserInfo ->
Bool ->
SourceName ->
SourceConfig 'MSSQL ->
MutationDB 'MSSQL Void (UnpreparedValue 'MSSQL) ->
m (DBStepInfo 'MSSQL)
msDBMutationPlan userInfo stringifyNum sourceName sourceConfig mrf = do
go <$> case mrf of
MDBInsert annInsert -> executeInsert userInfo stringifyNum sourceConfig annInsert
MDBDelete annDelete -> executeDelete userInfo stringifyNum sourceConfig annDelete
MDBUpdate annUpdate -> executeUpdate userInfo stringifyNum sourceConfig annUpdate
MDBFunction {} -> throw400 NotSupported "function mutations are not supported in MSSQL"
where
go v = DBStepInfo @'MSSQL sourceName sourceConfig Nothing v
-- * Subscription
msDBSubscriptionPlan ::
forall m.
( MonadError QErr m,
MonadIO m,
MonadBaseControl IO m
) =>
UserInfo ->
SourceName ->
SourceConfig 'MSSQL ->
Maybe G.Name ->
RootFieldMap (QueryDB 'MSSQL Void (UnpreparedValue 'MSSQL)) ->
m (LiveQueryPlan 'MSSQL (MultiplexedQuery 'MSSQL))
msDBSubscriptionPlan UserInfo {_uiSession, _uiRole} _sourceName sourceConfig namespace rootFields = do
(reselect, prepareState) <- planSubscription (OMap.mapKeys _rfaAlias rootFields) _uiSession
cohortVariables <- prepareStateCohortVariables sourceConfig _uiSession prepareState
let parameterizedPlan = ParameterizedLiveQueryPlan _uiRole $ MultiplexedQuery' reselect
pure $
LiveQueryPlan parameterizedPlan sourceConfig cohortVariables namespace
prepareStateCohortVariables :: (MonadError QErr m, MonadIO m, MonadBaseControl IO m) => SourceConfig 'MSSQL -> SessionVariables -> PrepareState -> m CohortVariables
prepareStateCohortVariables sourceConfig session prepState = do
(namedVars, posVars) <- validateVariables sourceConfig session prepState
let PrepareState {sessionVariables} = prepState
pure $
mkCohortVariables
sessionVariables
session
namedVars
posVars
-- | Ensure that the set of variables (with value instantiations) that occur in
-- a (RQL) query produce a well-formed and executable (SQL) query when
-- considered in isolation.
--
-- This helps avoiding cascading failures in multiplexed queries.
--
-- c.f. https://github.com/hasura/graphql-engine-mono/issues/1210.
validateVariables ::
(MonadError QErr m, MonadIO m, MonadBaseControl IO m) =>
SourceConfig 'MSSQL ->
SessionVariables ->
PrepareState ->
m (ValidatedQueryVariables, ValidatedSyntheticVariables)
validateVariables sourceConfig sessionVariableValues prepState = do
let PrepareState {sessionVariables, namedArguments, positionalArguments} = prepState
-- We generate a single 'canary' query in the form:
--
-- SELECT ... [session].[x-hasura-foo] as [x-hasura-foo], ... as a, ... as b, ...
-- FROM OPENJSON('...')
-- WITH ([x-hasura-foo] NVARCHAR(MAX)) as [session]
--
-- where 'a', 'b', etc. are aliases given to positional arguments.
-- Named arguments and session variables are aliased to themselves.
--
-- The idea being that if the canary query succeeds we can be
-- reasonably confident that adding these variables to a query being
-- polled will not crash the poller.
occSessionVars =
filterSessionVariables
(\k _ -> Set.member k sessionVariables)
sessionVariableValues
expSes, expNamed, expPos :: [Aliased Expression]
expSes = sessionReference <$> getSessionVariables occSessionVars
expNamed =
map
( \(n, v) -> Aliased (ValueExpression (RQLColumn.cvValue v)) (G.unName n)
)
$ Map.toList $ namedArguments
-- For positional args we need to be a bit careful not to capture names
-- from expNamed and expSes (however unlikely)
expPos =
zipWith
(\n v -> Aliased (ValueExpression (RQLColumn.cvValue v)) n)
(freshVars (expNamed <> expSes))
positionalArguments
projAll :: [Projection]
projAll = map ExpressionProjection (expSes <> expNamed <> expPos)
canaryQuery =
if null projAll
then Nothing
else
Just $
renderQuery
emptySelect
{ selectProjections = projAll,
selectFrom = sessionOpenJson occSessionVars
}
onJust
canaryQuery
( \q -> do
_ :: [[ODBC.Value]] <- mssqlRunReadOnly (_mscExecCtx sourceConfig) (`ODBC.query` q)
pure ()
)
pure
( ValidatedVariables $ txtEncodedColVal <$> namedArguments,
ValidatedVariables $ txtEncodedColVal <$> positionalArguments
)
where
renderQuery :: Select -> ODBC.Query
renderQuery = toQueryFlat . fromSelect
freshVars :: [Aliased a] -> [Text]
freshVars boundNames = filter (not . (`elem` map aliasedAlias boundNames)) chars
-- Infinite list of expression aliases.
chars :: [Text]
chars = [y T.<>> x | y <- [""] <|> chars, x <- ['a' .. 'z']]
sessionOpenJson :: SessionVariables -> Maybe From
sessionOpenJson occSessionVars =
nonEmpty (getSessionVariables occSessionVars)
<&> \fields ->
FromOpenJson $
Aliased
( OpenJson
(ValueExpression $ ODBC.TextValue $ lbsToTxt $ J.encode occSessionVars)
(pure (sessField <$> fields))
)
"session"
sessField :: Text -> JsonFieldSpec
sessField var = StringField var Nothing
sessionReference :: Text -> Aliased Expression
sessionReference var = Aliased (ColumnExpression (TSQL.FieldName var "session")) var
-- * Remote Relationships (e.g. DB-to-DB Joins, remote schema joins, etc.)
-- | Construct an action (i.e. 'DBStepInfo') which can marshal some remote
-- relationship information into a form that SQL Server can query against.
--
-- XXX: Currently unimplemented; the Postgres implementation uses
-- @jsonb_to_recordset@ to query the remote relationship, however this
-- functionality doesn't exist in SQL Server.
--
-- NOTE: The following typeclass constraints will be necessary when implementing
-- this function for real:
--
-- @
-- MonadQueryTags m
-- Backend 'MSSQL
-- @
msDBRemoteRelationshipPlan ::
forall m.
( MonadError QErr m
) =>
UserInfo ->
SourceName ->
SourceConfig 'MSSQL ->
-- | List of json objects, each of which becomes a row of the table.
NonEmpty J.Object ->
-- | The above objects have this schema
--
-- XXX: What is this for/what does this mean?
HashMap RQLTypes.FieldName (RQLTypes.Column 'MSSQL, RQLTypes.ScalarType 'MSSQL) ->
-- | This is a field name from the lhs that *has* to be selected in the
-- response along with the relationship.
RQLTypes.FieldName ->
(RQLTypes.FieldName, SourceRelationshipSelection 'MSSQL Void UnpreparedValue) ->
m (DBStepInfo 'MSSQL)
msDBRemoteRelationshipPlan _userInfo _sourceName _sourceConfig _lhs _lhsSchema _argumentId _relationship = do
throw500 "mkDBRemoteRelationshipPlan: SQL Server (MSSQL) does not currently support generalized joins."